Polymeric-based microparticles and fibers are tailorable for a wide range of common industrial and biomedical applications, while multiwalled carbon nanotubes (MWCNTs) are among the most useful macromolecules based on their outstanding electronic, mechanical, and optical properties at the nanoscale. If one combines these nanostructures with various polymeric precursors, their range of potential applications becomes even greater. One of the simplest and most affordable methods for fabricating micro- and nanostructures is electrospinning. Herein we demonstrate how MWCNTs may be used to produce tailor-made organic–organic poly­(vinylpyrrolidone) (PVP) microparticles and fibers via electrospinning by studying their structural, vibrational, rheological, and mechanical properties’ dependence on their solvent (ethanol (EtOH) or dimethyl­formamide (DMF)) and resulting morphology. Specifically, we find clear differences in morphologies from perfectly spherical and isolated microparticles to fibers mats, or a combination of fibers with entangled beads, with solvent type and concentration. On the basis of our findings, we propose that the mechanism governing the shape and size of the particles is a competition between the solvent’s surface tension, dielectric constant, and viscoelastic properties. We show, based on both our experimental results and density functional theory (DFT) calculations, that OH functionalization of the MWCNTs is essential for achieving high PVP coverages and promoting the stability of the resulting PVP/MWCNT nanocomposite. Finally, by fabricating PVP/MWCNT fiber mats, we demonstrate that low concentrations (0.01–0.1 wt %) of MWCNTs led to a qualitative improvement (∼250%) in the resulting mechanical properties, i.e., a reinforced composite. These results show how by controlling the solvent’s dielectric constant, surface tension, and polymer concentration, one may produce tailor-made polymeric nanomaterials in combination with other organic/inorganic nanoparticles, i.e., silver, gold, or carbon allotropes, for next-generation applications.

Emerging contaminants (ECs) are causing negative effects on the environment and even on people, so their removal has become a priority worldwide. Adsorption and the associated technologies where this process occurs (filtration/biofiltration) have gained great interest, due to its low cost, easy operation, and effectiveness mainly in the removal (up to 100%) of lipophilic ECs (log Kow > 4). Activated carbon continues to be the most efficient material in the removal of ECs (>850 mg/g). However, other conventional materials (activated carbon, clays, zeolites) and non-conventional materials (agro-industrial/forestry/industrial residues, nanomaterials, among others) have shown efficiencies greater than 90%. Adsorption depends on the physicochemical properties of the materials and ECs. Thus, physical/chemical/thermal modifications and nanomaterial synthesis are the most used procedures to improve adsorption capacity. A material with good adsorptive properties could be used efficiently in filtration/biofiltration technologies. Agro-industrial residues are promising alternatives to be used in these technologies, due to their high availability, low toxicity, and adsorption capacities (up to 350 mg/g). In filtration/biofiltration technologies, the material, in addition to acting as adsorbent, plays a fundamental role in operation and hydraulics. Therefore, selecting the appropriate material improves the efficiency/useful life of the filter/biofilter.

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The performance of fibrous membrane composites fabricated via electrospinning is strongly influenced by the solution’s properties, process variables and ambient conditions, although a precise mechanism for controlling the properties of...

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Contamination of water by heavy metals is a major environmental concern due to the potential ecological impact on human health and aquatic ecosystems. In this work, we studied the chemical modification of various fruit peels such as banana (BP), granadilla (GP), and orange ones (OP) in order to obtain novel bio-adsorbents to improve the removal of Zn(II) ions from 50 mg·L−1 synthetic aqueous solutions. For this purpose, sodium hydroxide and calcium acetate were employed to modify the fruit peels. The moisture, extractives, lignin, hemicellulose, and cellulose contents of the raw materials were determined according to ASTM standards. The obtained bio-adsorbents were characterized by scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and thermogravimetric analysis (TGA). The results showed the OP bio-adsorbents performed better, especially when the concentration of the modifier solutions increased, e.g., the OP particles modified using 0.8 M NaOH and Ca(CH3COO)2 solutions resulted in 97% removal of Zn(II) contaminating ions and reached a maximum adsorption capacity of 27.5 mg Zn per gram of bio-adsorbent. The adsorption processes were found to follow a pseudo-second order model. The error function sum of square error indicated the Freundlich isotherm (non-linear regression) as best fit model. The obtained results are particularly interesting for material selection in wastewater treatment technologies based on contaminant adsorption.

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